CORS_wrapper.js

const http = require('http');
const httpRequest = require('request');

const API_ENDPOINT = 'http://<hostname>:<port>/<path-to-resource>';

function normalizePort(val) {
  const port = parseInt(val, 10);

  if (isNaN(port)) {
    // named pipe
    return val;
  }

  if (port >= 0) {
    // port number
    return port;
  }

  return false;
}

const port = normalizePort(process.env.PORT || '3000');

// Inject headers and relay the response
function handleRequest(request, response){
  
  httpRequest(API_ENDPOINT, (error, res, body) => {
    response.writeHead(res.statusCode, {
      'Content-Type': 'application/json',
      'Access-Control-Allow-Origin' : '*',
      'Access-Control-Allow-Methods': 'GET,PUT,POST,DELETE'
    });

    response.end(body);
  });  
}

//Create a server
var server = http.createServer(handleRequest);

server.listen(port);

server.on('error', onError);
server.on('listening', onListening);

/**
 * Event listener for HTTP server "error" event.
 */

function onError(error) {
  if (error.syscall !== 'listen') {
    throw error;
  }

  var bind = typeof port === 'string'
	   ? 'Pipe ' + port
	   : 'Port ' + port;

  // handle specific listen errors with friendly messages
  switch (error.code) {
    case 'EACCES':
      console.error(bind + ' requires elevated privileges');
      process.exit(1);
      break;
    case 'EADDRINUSE':
      console.error(bind + ' is already in use');
      process.exit(1);
      break;
    default:
      throw error;
  }
}

/**
 * Event listener for HTTP server "listening" event.
 */
function onListening() {
  var addr = server.address();
  var bind = typeof addr === 'string'
	   ? 'pipe ' + addr
	   : 'port ' + addr.port;
  console.log('Listening on ' + bind);
}